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Tuesday, 28 February 2012

Fasting and Chemotherapy

In a recent article on Low Carb Diets And Cancer, we looked at some interesting results of studies on low carb diets on established tumours. The conclusion to that study showed that a low carbohydrate, high protein diet:

...reduces blood glucose, insulin, and glycolysis, slows tumor growth, reduces tumor incidence, and works additively with existing therapies without weight loss or kidney failure. Such a diet, therefore, has the potential of being both a novel cancer prophylactic and treatment, warranting further investigation of its applicability in the clinic, especially in combination with existing therapies.

Well, you can’t get lower carb than not eating altogether, and that’s exactly what another new paper explores as an option. Published in the journal Science Translational Medicine, you get a clear idea of what it’s about from the title: Fasting Cycles Retard Growth of Tumors and Sensitize a Range of Cancer Cell
Types to Chemotherapy. As with the previous paper, much of the data in this paper comes from mice models of cancer. So, as always it’s important to keep in mind that what works in mice doesn’t necessarily work in humans. Aside from anything else, mice don’t have to cope with the stress of knowing they have cancer…With that caveat in mind, we can move on to see what the research team, lead by Dr Valter D. Longo, discovered. Firstly the team established that fasting can significantly slow tumour growth for a range of cancer types - they did this in the test tube first, and then followed up with mice. These experiments showed that fasting - and by this they mean complete withdrawal of all food - in mice did significantly slow tumour growth for a range of cancer types, including breast, melanoma, glioma and neuroblastoma. In the case of melanoma the effect of fasting seemed to disappear after a single cycle of fasting, but in the other tumour types the effect was more sustained.

However, the best results occurred when the fasting was combined with high dose chemotherapy. Again, there was a range of tumour types tested, along with a range of chemotherapy drugs - cyclophosphamide, etoposide and doxorubicin. By fasting before and after the chemotherapy was applied, two effects became clear. The first is that fasting seemed to lessen chemotherapy side effects - normal cells switched to a stressed state that protected them from the toxic effects of chemo, while the cancer cells carried on in their normal state and suffered the full brunt of the chemo. Secondly, the fasting seemed to make the cancer cells more sensitive to the chemo drugs, increasing the rate of tumour regression.

In the words of the authors of the paper:

…fasting cycles in combination with chemotherapy could extend the survival of advanced stage cancer patients by both retarding tumor progression and reducing side effects.

In terms of the actual degree of fasting, the authors are very specific. This is not about missing a meal or two before chemo. The results are based on fasting for 48-72 hours before and for 24 hours after chemotherapy. That’s a long time to go without food, and it’s clearly not intended for patients already weak, suffering from anorexia or cancer cachexia. While there’s some weight loss, this isn’t permanent and the weight is put back on after re-feeding. It’s also worth noting that the authors have also published a previous paper that described positive results in patients fasting as a way of reducing the side effects of chemotherapy.

The good news is that these results are of more than just academic interest. There are already a couple of clinical trials on-going - and so it may be that this is one dietary intervention that might make it into clinical practice in the future.

In the meantime - this is an area to watch. Remember also that this is a research paper - by its nature this is experimental. If you are a cancer patient thinking about doing something like this, please talk to your medical team as a matter of priority. It’s not something that should be undertaken without clear medical supervision.